Method and apparatus for cooling syngas within a gasifier system

ABSTRACT

A method of assembling a synthesis gas (syngas) cooler for a gasification system includes positioning a dip tube within a shell of the syngas cooler. The dip tube is configured to quench the syngas flowing through the shell and/or at least partially channel the syngas through the dip tube. The method also includes coupling an isolation tube to the dip tube such that the isolation tube is substantially concentrically aligned with, and radially outward of, the dip tube. The isolation tube is coupled in flow communication with a purge gas source and is configured to at least partially form a dynamic pressure seal. The method further includes coupling at least one of the isolation tube and the dip tube in fluid communication with a fluid retention chamber. The method also include at least partially filling the fluid retention chamber with fluid, thereby further forming the dynamic pressure seal.

BACKGROUND OF THE INVENTION

This invention relates generally to synthesis gas, or syngas, coolersfor use in a gasifier system, and, more specifically, to a quench systemfor use with a syngas cooler.

Some known gasification systems use two syngas coolers in series to coolsyngas, slag, and fly ash particles contained therein. Such systems canbe used advantageously because, typically, a first syngas cooler,typically a radiant syngas cooler, or RSC, incorporates slag and fly ashseparation and quenching means near a first syngas outlet thatfacilitates reducing the potential of fouling and plugging in a secondsyngas cooler. Fouling and plugging is a concern associated with thesecond syngas cooler, typically a convective syngas cooler, or CSC, dueto changes in heat transfer surface materials and configurations thatare used to effectively transfer heat, as well as changing flowconditions. Such a series cooler arrangement facilitates heat transferefficiency, however, a large capital investment in such a two syngascooler arrangement may not always be cost-effective. Furthermore, undercertain circumstances, such an arrangement may not effectively mitigatefouling and plugging.

Some other known gasification systems use a first syngas cooler similarto that described above, but unlike the arrangement described above,exclude the second syngas cooler, wherein an internal quench mechanismis incorporated near the outlet of the first syngas cooler. Although notproviding the same degree of heat recovery as described above, a singlecooler system can decrease capital costs, facilitate downstreamapplications of the syngas that requires moisture in the syngas, whilealso mitigating fouling and plugging. However, incorporating aneffective quench arrangement with a syngas outlet presents challenges,including how best to facilitate the quenching operation, whilemitigating corrosion as well as sealing and controlling a differentialpressure across portions of the syngas cooler heat transfer surfacesnormally associated with such systems.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a method of assembling a synthesis gas (syngas) coolerfor a gasification system is provided. The method includes positioning adip tube within a shell of the syngas cooler. The dip tube is configuredto at least one of at least partially quench at least a portion of thesyngas flowing through the shell and at least partially channel at leasta portion of the syngas through the dip tube. The method also includescoupling an isolation tube to the dip tube such that the isolation tubeis substantially concentrically aligned with, and radially outward of,the dip tube. The isolation tube is coupled in flow communication with apurge gas source and is configured to at least partially form a dynamicpressure seal. The method further includes coupling at least one of theisolation tube and the dip tube in fluid communication with a fluidretention chamber. The method also includes at least partially fillingthe fluid retention chamber with fluid, thereby further forming thedynamic pressure seal.

In a further aspect, a synthesis gas (syngas) cooler for use within agasification system is provided. The syngas cooler includes a shell anda dip tube coupled within the shell. The dip tube is configured to atleast partially quench at least a portion of a syngas flowing throughthe shell and/or at least partially channel a portion of the syngasthrough the dip tube. The syngas cooler also includes an isolation tubecoupled to the dip tube such that the isolation tube is substantiallyconcentrically aligned with, and radially outward of, the dip tube. Theisolation tube is coupled in flow communication with a purge gas sourceand is configured to at least partially form a dynamic pressure seal.The syngas cooler further includes a fluid retention chamber coupled inflow communication with at least one of the isolation tube and the diptube. The fluid retention chamber is at least partially filled withfluid and is configured to further form the dynamic pressure seal.

In another aspect, a gasification system is provided. The gasificationsystem includes at least one gasifier configured to produce a synthesisgas (syngas). The system also includes at least one syngas coolercoupled in flow communication with the gasifier. The syngas coolerincludes a shell and a dip tube coupled within the shell. The dip tubeis configured to at least partially quench at least a portion of asyngas flowing through the shell and/or at least partially channel aportion of the syngas through the dip tube. The syngas cooler alsoincludes an isolation tube coupled to the dip tube such that theisolation tube is substantially concentrically aligned with, andradially outward of, the dip tube. The isolation tube is coupled in flowcommunication with a purge gas source and is configured to at leastpartially form a dynamic pressure seal. The syngas cooler furtherincludes a fluid retention chamber coupled in flow communication with atleast one of the isolation tube and the dip tube. The fluid retentionchamber is at least partially filled with fluid and is configured tofurther form the dynamic pressure seal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic view of an exemplary integrated gasificationcombined cycle power generation system;

FIG. 2 is a schematic cross-sectional view of an exemplary syngas coolerthat may be used with the system shown in FIG. 1; and

FIG. 3 is a schematic cross-sectional view of an alternative syngascooler that may be used with the system shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic diagram of an exemplary integrated gasificationcombined-cycle (IGCC) power generation system 10. IGCC system 10generally includes a main air compressor 12, an air separation unit(ASU) 14 coupled in flow communication to compressor 12, a gasifier 16coupled in flow communication to ASU 14, a syngas cooler 18 coupled inflow communication to gasifier 16, a gas turbine engine 20 coupled inflow communication with syngas cooler 18, and a steam turbine engine 22coupled in flow communication with syngas cooler 18.

In operation, compressor 12 compresses ambient air that is thenchanneled to ASU 14. In the exemplary embodiment, in addition tocompressed air from compressor 12, compressed air from a gas turbineengine compressor 24 is supplied to ASU 14. Alternatively, compressedair from gas turbine engine compressor 24 is supplied to ASU 14, ratherthan compressed air from compressor 12 being supplied to ASU 14. In theexemplary embodiment, ASU 14 uses the compressed air to generate oxygenfor use by gasifier 16. More specifically, ASU 14 separates thecompressed air into separate flows of oxygen (O₂) and a gas by-product,sometimes referred to as a “process gas”. The O₂ flow is channeled togasifier 16 for use in generating synthesis gases, referred to herein as“syngas” for use by gas turbine engine 20 as fuel, as described below inmore detail.

The process gas generated by ASU 14 includes nitrogen and will bereferred to herein as “nitrogen process gas” (NPG). The NPG may alsoinclude other gases such as, but not limited to, oxygen and/or argon.For example, in the exemplary embodiment, the NPG includes between about95% and about 100% nitrogen. In the exemplary embodiment, at least someof the NPG flow is vented to the atmosphere from ASU 14, and at leastsome of the NPG flow is injected into a combustion zone (not shown)within a gas turbine engine combustor 26 to facilitate controllingemissions of engine 20, and more specifically to facilitate reducing thecombustion temperature and reducing nitrous oxide emissions from engine20. In the exemplary embodiment, IGCC system 10 includes a NPGcompressor 28 for compressing the nitrogen process gas flow before beinginjected into a combustion zone (not shown) of gas turbine enginecombustor 26.

In the exemplary embodiment, gasifier 16 converts a mixture of fuelsupplied from a fuel supply 30, O₂ supplied by ASU 14, steam, and/orliquid water, and/or slag additive into an output of syngas for use bygas turbine engine 20 as fuel. Although gasifier 16 may use any fuel,gasifier 16, in the exemplary embodiment, uses coal, petroleum coke,residual oil, oil emulsions, tar sands, and/or other similar fuels.Furthermore, in the exemplary embodiment, syngas generated by gasifier16 includes carbon monoxide, hydrogen, and carbon dioxide. In theexemplary embodiment, gasifier 16 is an entrained flow gasifier,configured to discharge syngas, slag, and fly ash vertically downwardinto syngas cooler 18. Alternatively, gasifier 16 may be any type andconfiguration that facilitates operation of syngas cooler 18 asdescribed herein.

In the exemplary embodiment, syngas generated by gasifier 16 ischanneled to syngas cooler 18 to facilitate cooling the syngas, asdescribed in more detail below. The cooled syngas is channeled fromcooler 18 to a clean-up device 32 that facilitates cleaning the syngasbefore it is channeled to gas turbine engine combustor 26 for combustiontherein. Carbon dioxide (CO₂) may be separated from the syngas duringclean-up and, in the exemplary embodiment, may be vented to theatmosphere. Gas turbine engine 20 drives a first generator 34 thatsupplies electrical power to a power grid (not shown). Exhaust gasesfrom gas turbine engine 20 are channeled to a heat recovery steamgenerator (HRSG) 36 that generates steam for driving steam turbine 22.Power generated by steam turbine 22 drives a second generator 38 thatalso provides electrical power to the power grid. In the exemplaryembodiment, steam from heat recovery steam generator 36 may be suppliedto gasifier 16 for generating syngas.

Furthermore, in the exemplary embodiment, system 10 includes a pump 40that supplies heated water from HRSG 36 to syngas cooler 18 tofacilitate cooling syngas channeled from gasifier 16. The heated wateris channeled through syngas cooler 18 wherein water is converted tosteam. Steam from cooler 18 is then returned to HRSG 36 for use withingasifier 16, syngas cooler 18, and/or steam turbine 22.

FIG. 2 is a schematic cross-sectional view of a lower portion of anexemplary syngas cooler 100 that may be used with system 10 (shown inFIG. 1). Syngas cooler 100 is an exemplary embodiment of syngas cooler18 (shown in FIG. 1) and is a radiant syngas cooler (RSC). Syngas cooler100 includes a plurality of heat exchange devices, such as, but notbeing limited to, a heat exchange wall 104 and/or platen assemblies (notshown), positioned within a cooler shell 102. In the exemplaryembodiment, heat exchange wall 104 substantially isolates shell 102 fromsyngas 110 flowing through cooler 100. Also, in the exemplaryembodiment, shell 102 has a substantially circular cross-sectional shapehaving a longitudinal axis, or centerline 106 and a shell radius R₁.Alternatively, shell 102 may have any cross-sectional shape thatfacilitates operation of cooler 100 as described herein. Radii, asdescribed herein, are measured outward from centerline 106 unlessotherwise defined. A main syngas flowpath 108 is defined within cooler100 along which syngas 110 and/or particulates 112 generally flow. Insome embodiments, shell 102 and wall 104 are fabricated from anymaterial that facilitates preventing syngas 110 and particulate material112 from substantially adhering to shell 102 and wall 104.

In the exemplary embodiment, flowpath 108 is generally aligned parallelwith centerline 106. Although syngas 110 and particulates 112 are shownas separate flows, it will be understood that particulates 112 may beentrained with and/or suspended within syngas 110 such that particulates112 and syngas 110 constitute a combined flow. Furthermore, as usedherein, the terms “upstream” and “downstream” are defined with respectto main syngas flowpath 108, such that a top (not shown) of cooler 100is considered to be “upstream” from a bottom 114 of cooler 100. Also, asused herein, particulates 112 is defined to include molten ashparticulates, char, and fly ash particulates.

Cooler 100 also includes a quench chamber 116 that is downstream fromthe heat exchange devices. Chamber 116 facilitates rapidly coolingsyngas 110 and/or particulates 112. More specifically, a lower wall 118separates quench chamber 116 from a heat exchange section 120 of cooler100 including the heat exchange devices (as described above) therein. Inone embodiment, lower wall 118 is formed from a plurality of heatexchange tubes (not shown). In another embodiment, lower wall 118 isfabricated from a refractory liner material. Moreover, in someembodiments, quench chamber 116 and lower wall 118 are fabricated fromany material that facilitates preventing syngas 110 and particulatematerial 112 from substantially adhering to quench chamber 116 and lowerwall 118. In the exemplary embodiment, lower wall 118 is substantiallyconical and tapers inwardly, or converges from an upstream end 122 oflower wall 118 to a downstream end 124 of lower wall 118. Downstream end124 defines a first inner diameter ID₁. Moreover, upstream end 122 maybe coupled to, and/or positioned adjacent to, a downstream end 126 ofheat exchange wall 104. Alternatively, lower wall 118 may be coupled toany other suitable component within syngas cooler 100 that facilitatesoperation of cooler 100 as described herein.

In the exemplary embodiment, quench chamber 116 includes a dip tube 128,a quench ring 129 and/or quench spray devices (not shown), an isolationtube 130, a splash plate 132, a fluid retention chamber, or water bath134, a sump 136, a blowdown line 138, a water bath fluid makeup supplyline (not shown) and at least one syngas outlet 140. In someembodiments, dip tube 128 and isolation tube 130 are fabricated from anymaterial that facilitates preventing syngas 110 and particulate material112 from substantially adhering to dip tube 128 and isolation tube 130.

Water bath 134 includes bath water 142, wherein although water 142 isdescribed herein as the fluid used to quench syngas 110 and/orparticulates 112, any suitable non-reactive fluid may be used forquenching. In the exemplary embodiment, quench ring 129 and/or quenchspray devices (not shown) are situated at an upstream end 150 of diptube 128, and are used to wet and cool an inner wall 174 of dip tube128, as well as facilitate cooling and scrubbing of syngas 110 andparticulates 112. Dip tube 128 defines a second inner diameter ID₂.

To facilitate mitigating deposition of molten particulates 112 on diptube 128 due to direct contact of relatively hot particulates 112 withdip tube 128, ID₂ is greater than ID₁. That is, dip tube 128, as well asquench ring 129 and/or the quench spray devices (not shown), arepreferably somewhat recessed relative to downstream end 124 of lowerwall 118. Quench ring 129 and/or quench spray devices may be in anynumber, orientation, and/or design that facilitates the operation of thesyngas cooler 100 as provided herein. In an alternative embodiment,syngas cooler 100 has no quench ring 129 and/or quench spray devicessituated at the upstream end 150 of dip tube 128. Also, alternatively,quench ring 129 is a gas quench manifold with at least one gas outlet(not shown) that is configured to channel cooling gas into primary zone144. Further, in alternative embodiments, any means for quenching,scrubbing and cooling syngas 110, cooling and flushing radially interiorportions of dip tube 128, and cooling and flushing other components inquench chamber 116 are provided.

Dip tube 128, quench ring 129, and isolation tube 130 each have asubstantially circular cross-section. In other embodiments, tubes 128and/or 130, and/or quench ring 129 have any cross-sectional shape thatfacilitates operation of cooler 100 as described herein. In theexemplary embodiment, dip tube 128, quench ring 129, and isolation tube130 are substantially concentrically aligned with centerline 106. Morespecifically, dip tube 128 has a dip tube radius R₂ and isolation tube130 has an isolation tube radius R₃, wherein in the exemplaryembodiment, radius R₂ is less than radius R₃, and radius R₃ is less thanradius R₁. As such, a primary quench zone 144 is defined within dip tube128, a first substantially annular passage 146 is defined between diptube 128 and isolation tube 130, and a second substantially annularpassage 148 is defined between isolation tube 130 and shell 102.

Moreover, in the exemplary embodiment, upstream end 150 of dip tube 128is coupled proximate to an upstream end 151 of splash plate 132, anupstream end 152 of isolation tube 130 is coupled proximate to adownstream end 153 of splash plate 132, and a downstream end 154 of diptube 128 is positioned upstream from a downstream end 156 of isolationtube 130. Each upstream end 150 and 151 is positioned proximate to lowerwall 118. Specifically, in the exemplary embodiment, each upstream end150 and 151 is positioned proximate to downstream end 124 of lower wall118. Downstream end 154 of dip tube 128 extends into water bath 134,thereby facilitating quenching and scrubbing of syngas 110 andparticulates 112 exiting downstream end 154 by water 142.

Downstream end 156 of isolation tube 130 also extends into water bath134, thereby forming a dynamic pressure seal (discussed further below)between annular passage 146 and annular passage 148. In the exemplaryembodiment, downstream end 154 of dip tube 128 is serrated to helpdistribute syngas 110 as it enters into water bath 134 beneath dip tube128. Similarly, in the exemplary embodiment, downstream end 156 ofisolation tube 130 is serrated to help distribute a purge gas 190(discussed further below) and/or syngas 110 to flow within water bath134, between annular passage 146 and annular passage 148. In analternative embodiment, downstream ends 154 and/or 156 of tubes 128and/or 130, respectively, may have any suitable shape that facilitatesoperation of cooler 100 as described herein.

In the exemplary embodiment, isolation tube 130 includes at least onepurge vent 147 defined in an outer wall 149 of isolation tube 130. Purgevent 147 is upstream of water bath 134, is selectively operable, and hasa downward-pointing orientation in passage 148 to facilitate channelingsyngas 110 downward during backflow conditions as described furtherbelow. For example, when purge vent 147 is open during normaloperations, purge gas 190 flows through purge vent 147 from passage 148through isolation tube 130 into passage 146, as will be described inmore detail below.

As described herein, purge gas 190 is a non-reactive gas that includes,but is not limited to, inert nitrogen gas (N₂) or carbon monoxide (CO).Such non-reactive gases are typically not associated with adversereactions with the predetermined materials used to manufacture cooler100 and the processes defined herein, wherein such adverse reactionsinclude, but are not limited to, accelerated corrosion. Also, asdescribed here, “selectively operable” is defined as modulated byintrinsic mechanical properties and characteristics, an automatedelectronic control system (not shown) or manual operator-assisteddevices (not shown). Alternatively, vents 147 include fixed openingswherein purge gas 190 flow through vents 147 is substantiallyexclusively controlled by differential pressure between passages 148 and146.

A predetermined rate of flow of purge gas 190 into isolation tube 130 ata predetermined pressure substantially mitigates syngas 110, moisture,and particulates 112 entering into passage 148 from water 142.Consequently, purge vents 147 are sized to facilitate a continuous flowof purge gas 190 from annular passage 148 to annular passage 146 thatfacilitates removal of contaminants from between heat transfer wall 104and lower wall 118, and shell 102, at pressure differentials well withinthe operating range of differential pressures across heat transfer wall104, lower wall 118, and isolation tube 130. Although only two purgevents 147 are illustrated, it should be understood isolation tube 130may include any number of purge vents 147. In an alternative embodiment,at least one purge vent 147 is defined within wall 149. In anotheralternative embodiment, at least one purge vent 147 has a fixed opening.In a further alternative embodiment, isolation tube 130 does not includeany purge vents 147.

Vents 147 operate in cooperation with annular passage 148 to maintain asmall, but acceptable differential pressure radially across isolationtube 130, wherein purge gas 190 is continuously purging the passage 148between heat transfer wall 104 and shell 102. Such purging facilitatesuse of lower-temperature, less corrosion-resistant, and less expensivealloys and mitigates a potential for syngas 110 to enter passage 148.Vents 147 are operable such that purge gas 190 pressure in annularpassage 148 is consistently maintained within a narrow sliding pressureband, thereby mitigating pressure cycling and facilitating maintenanceof a comfortable margin from predetermined pressure and differentialpressure limits. Moreover, in embodiments wherein reverse flowconditions, that is, flow of syngas 110 from passage 146 into passage148, are permitted, containment of such syngas 110 flow withinpredetermined parameters can be facilitated by vents 147.

In the exemplary embodiment, vents 147 are modulated based upon primaryvariables that include, but are not limited to, predetermineddifferential pressure values across vent 147. Moreover, such selectiveoperation is associated with predetermined operational conditions thatinclude, but are not limited to, startup and shutdown and/orpressurization and depressurization of gasifier 16 (shown in FIG. 1).

In an alternative embodiment, vent spray devices (not shown) arepositioned proximate to vents 147. Such devices spray water and/oradditives in a pattern that facilitates a reduction in fouling andplugging of vents 147 and are selectively operable as described above.Specifically, such devices are in operation continuously or aremodulated intermittently based upon primary variables that include, butare not limited to, differential pressure across vent 147 approaching apredetermined value wherein syngas 110 is likely to flow through vent147 rather than purge gas 190. Moreover, such selective operation isassociated with predetermined operational conditions that include, butare not limited to, startup and/or pressurization of gasifier 16 (shownin FIG. 1), wherein predetermined syngas 110 flows through vent 147 areanticipated and facilitated. Furthermore, such selective operation maybe based on predetermined temporal parameters, for example, but notlimited to, a five-minute spray period once every hour.

Moreover, in the exemplary embodiment, annular passages 148 are coupledin flow communication with a purge gas supply system (not shown) thatfacilitates operation of cooler 100 as described herein by modulatingoverall purge gas 190 flow into cooler 100 using selectively-operablemechanisms as described herein. That is, purge gas 190 flow and pressuremay be increased during operation modes such as startup and cooler 100pressurization, or in response to changing conditions within cooler 100such as changes in differential pressure across isolation tube 130. Suchsupply system operates in cooperation with vents 147 to mitigate apotential for syngas 110 to enter a region of passage 148 between wall104 and shell 102.

Furthermore, cooler 100 includes sufficient instrumentation to monitorpredetermined differential pressures and flow rates associated withpurge gas 190 and syngas 110. Such instrumentation includes, but is notlimited to, vent 147 and wall 104 differential pressure (d/p) cells (notshown) that penetrate respective and proximate walls, as well asassociated transmitters (not shown) coupled in data communication withthe d/p cells.

In the exemplary embodiment, cooler 100 also includes at least onebaffle tray 155 extending from an inner wall 157 of shell 102. Baffletray 155 facilitates eliminating non-evaporated entrained water dropletsand particulate material 112 along inner wall 157. Specifically, in theexemplary embodiment, baffle tray 155 has a substantially V-shapedcross-sectional shape with a first portion 159 coupled to inner wall 157and a second portion 165 extending from first portion 159 at an angle θ.Furthermore, in the exemplary embodiment baffle tray 155 includescollection and drainage means (not shown) that substantially reduce there-entrainment of any captured water and particulate material 112.Alternatively, baffle tray 155 has any cross-sectional shape thatfacilitates operation of cooler 100 as described herein. Moreover, insome embodiments, baffle tray 155 is fabricated from any material thatfacilitates preventing syngas 110, water 142 and particulate material112 from substantially adhering to baffle tray 155. Any number of baffletrays 155 positioned anywhere within cooler 100 that facilitateoperation of cooler 100 as described herein are used.

In an alternative embodiment, baffle tray spray devices (not shown) arepositioned proximate to baffle tray 155. Such devices spray water and/oradditives in a pattern that facilitates a reduction in fouling andplugging of baffle tray 155 and are selectively operable as describedabove. Specifically, such spray devices are in operation continuously orare modulated intermittently based upon primary variables that include,but are not limited to, differential pressure across baffle plate 155approaching a predetermined value wherein flow of purge gas 190 downwardthrough passage 148 is diminished such that syngas 110 is likely to flowthrough vent 147 rather than purge gas 190. Moreover, such selectiveoperation is associated with predetermined operational conditions thatinclude, but are not limited to, startup and/or pressurization ofgasifier 16 (shown in FIG. 1), wherein increased particulate flow 112 isanticipated. Furthermore, such selective operation may be based onpredetermined temporal parameters, for example, but not limited to, afive-minute spray period once every hour.

A third passage 160 is defined between splash plate 132 and shell 102.Splash plate 132 facilitates retaining syngas 110 and water 142 withinisolation tube 130. In the exemplary embodiment, splash plate 132 isgenerally annular and extends between upstream end 151 and downstreamend 153. In the exemplary embodiment, downstream end 153 of splash plate132 is coupled proximate to upstream end 152 of isolation tube 130and/or to heat exchange wall downstream end 126.

In the exemplary embodiment, splash plate 132 is generallyfrusto-conical. Specifically, in the exemplary embodiment, upstream end151 of splash plate 132 has radius R₂ (as described above) anddownstream end 153 of splash plate 132 has radius R₃ (as describedabove) that is larger than radius R₂. More specifically, in theexemplary embodiment, splash plate 132 diverges from upstream end 151towards downstream end 153 such that plate 132 is at least partiallyconical. Alternatively, splash plate 132 may have any shape thatfacilitates operation of cooler 100 as described herein. Moreover,splash plate 132 is fabricated from any material that facilitatespreventing syngas 110, water 142, and particulate material 112 fromsubstantially adhering to splash plate 132. As such, splash plate 132facilitates preventing accumulation of particulates 112 in syngas 110 aswell as knockout of non-evaporated entrained water droplets, such thatparticulates 112 and water droplets (not shown) fall into water bath 134after contacting splash plate 132.

At least one syngas outlet 140 is defined between splash plate 132 andshell 102 such that syngas outlet 140 is in flow communication withthird passage 160. Outlet 140 channels syngas 110 from isolation tube130 to a component outside of shell 102. As shown in FIG. 2, cooler 100includes two outlets 140 extending from within isolation tube 130through splash plate 132 and through shell 102. Although only twooutlets 140 are shown in FIG. 2, alternatively, cooler 100 may includeany number of outlets 140 that facilitate operation of cooler 100 asdescribed herein.

In the exemplary embodiment, each outlet 140 is a cylindrical tube thathas a generally arcuate cross-sectional profile extending between afirst end 162 and a second end 164. Alternatively, outlet 140 may haveany shape that facilitates operation of cooler 100 as described herein.Specifically, in the exemplary embodiment, outlet 140 extends from firstend 162, positioned within isolation tube 130 near upstream end 152,through splash plate 132, and through shell 102. In the exemplaryembodiment, outlet second end 164 may be coupled to cleanup device 32(shown in FIG. 1), gas turbine engine 20 (shown in FIG. 1), and/or anyother suitable component that facilitates operation of system 10 andcooler 100 as described herein.

In the exemplary embodiment, a plurality of seals 166 are positionedbetween splash plate 132 and outlet 140 to facilitate coupling plate 132and outlet 140 together without leakage. Specifically, seals 166 areeach positioned along an intersection 141 defined between plate 132 andoutlet 140 to facilitate preventing leakage of syngas 110 and/or water142 through intersection 141 of plate 132 and outlet 140. Seals 166extend circumferentially about outlet 140. In the exemplary embodiment,seals 166 are water seals. Alternatively, seals 166 may be floatingcollar seals or any other seals that facilitate operation of cooler 100as described herein. Also, alternatively, seals 166 have bellows-typedevices (not shown). Further, alternatively, cooler 100 has any thermalexpansion mechanism that mitigates deleterious thermal expansion effectsbetween shell 102, outlets 140, plate 132, and isolation tube 130.Moreover, alternatively, thermal expansion effects within cooler 100 maybe mitigated by methods that include, but are not limited to, use of aslip joint or a bellows-type mechanism between lower wall 118 and splashplate 132, as well as material selection for lower wall 118 and plate132.

In an alternative embodiment, seal spray devices (not shown) arepositioned proximate to seals 166. Such devices spray water and/oradditives in a pattern that facilitates a reduction in particulatebuildup and fouling of seals 166 and are selectively operable asdescribed above. Specifically, such spray devices are in operationcontinuously or are modulated intermittently based upon primaryvariables that include, but are not limited to, differential pressureacross seals 166 within passage 148 approaching a predetermined valuewherein flow of purge gas 190 downward through passage 148 is diminishedsuch that syngas 110 is likely to flow through vent 147 rather thanpurge gas 190. Moreover, such selective operation is associated withpredetermined operational conditions that include, but are not limitedto, startup and/or pressurization of gasifier 16 (shown in FIG. 1),wherein increased particulate flow 112 is anticipated. Furthermore, suchselective operation may be based on predetermined temporal parameters,for example, but not limited to, a five-minute spray period once everyhour.

In another alternative embodiment, there are no seals 166, and theoutlet of splash plate 132 and inlet of outlet 140 are adjacent to, oroverlap, one another. Moreover, alternatively, splash plate 132 andoutlet 140 can be arranged in any manner that facilitates operation ofsyngas cooler 100 as described herein. The seal spray devices describedabove may still be employed in this embodiment to mitigate particulatebuildup.

In a further alternative embodiment, a gap (not shown) is definedbetween the outlet of splash plate 132 and inlet of outlet 140, whereinthe gap is sized to allow for free differential thermal growth betweensplash plate 132 and outlet 140. Furthermore, in this alternativeembodiment, the gap is sized to provide an equivalent fixed orificethrough which purge gas 190 can pass, instead of, or in addition to, oneor more fixed opening vents 147.

In this alternative embodiment, gap spray devices (not shown) arepositioned proximate to the gap defined between the outlet of splashplate 132 and inlet of outlet 140. Such devices spray water and/oradditives in a pattern that facilitates a reduction in particulatebuildup and fouling of the gap and are selectively operable as describedabove. Specifically, such spray devices are in operation continuously orare modulated intermittently based upon primary variables that include,but are not limited to, differential pressure across the gap betweenpassage 148 and passage 146 approaching a predetermined value whereinflow of purge gas 190 through the gap is diminished such that syngas 110is likely to flow through the gap rather than purge gas 190. Moreover,such selective operation is associated with predetermined operationalconditions that include, but are not limited to, startup and/orpressurization of gasifier 16 (shown in FIG. 1), wherein increasedparticulate flow 112 is anticipated. Furthermore, such selectiveoperation may be based on predetermined temporal parameters, forexample, but not limited to, a five-minute spray period once every hour.

In the exemplary embodiment, each outlet 140 includes at least one sprayinjector 173 coupled thereto that channels a spray fluid stream 177 intooutlet 140. Specifically, each spray injector 173 is coupled to an innersurface 175 of outlet 140. Alternatively, each spray injector 173 iscoupled to any surface that facilitates operation of cooler 100 asdescribed herein. Moreover, in the exemplary embodiment, spray injector173 is coupled within outlet 140 such that flow discharged therefrom isdischarged longitudinally downward substantially in diametric oppositionagainst the longitudinally upward flow of syngas 110 into outlet 140.Alternatively, at least one spray injector 173 is oriented to dischargefluid stream 177 in a direction that is at least partially oblique to atleast a portion of syngas 110 flow within outlet 140. Also,alternatively, at least one spray injector 173 is oriented to dischargefluid stream 177 in a direction that is substantially parallel to andcoincident with at least a portion of syngas 110 flow within outlet 140.Further, alternatively, at least one spray injector 173 is oriented inany direction that facilitates operation of syngas cooler 100 asdescribed herein. Moreover, alternatively, injector 173 is a gasinjector that forms a gas quenching stream 177.

Moreover, each spray injector 173 is selectively operable as describedabove. Typically, in the exemplary embodiment, spray injector 173 is incontinuous operation with substantially constant flow rates. Under someconditions, fluid flow rates may be modulated as a function of a mode ofoperation. Alternatively, any periodicity of spray operation with anyfluid flow rates that facilitate operation of cooler 100 as describedherein are used. When each spray injector 173 is in operation, sprayinjector 173 injects fluid spray stream 177 as described above. Sprayinjector 173 and spray stream 177 facilitate eliminating non-evaporatedentrained water droplets, and substantially reduces and/or preventsaccumulation of particulates 112, and/or water 142 from along wallsand/or surfaces of components within cooler 100 that include, but arenot limited to, an outer surface 178 of dip tube 128, an inner surface180 of isolation tube 130, and at least a portion of surface 175 ofoutlet 140.

Furthermore, spray injector 173 and stream 177 facilitate furthercooling of syngas 100. Moreover, spray injector 173 and spray stream 177may be adjusted to mitigate accumulation and agglomeration ofparticulates 112 within water bath 134 and sump 136. As such, with lessaccumulation on walls and/or surfaces of components within cooler 100,as well as less agglomeration in water 142, less plugging and/or foulingof such components occurs. Outlet 140 includes any number of sprayinjectors 173 that enables cooler 100 to function as described herein.In an alternative embodiment, outlet 140 does not include any sprayinjectors 173. In a still further alternative embodiment, at least onespray injector 173 is coupled to splash plate 132, isolation tube 130,and/or any suitable component of cooler 100 that facilitates operationof cooler 100 as described herein.

As described above, fluid 177 discharged from spray injector 173 mayflow downstream into water bath 134. In the exemplary embodiment, waterbath 134 includes water 142, sump 136, and blowdown line 138. Water bath134 forms a portion of quench chamber 116 that is configured to retainwater 142 therein. Although water bath 134 is shown and described ashaving water 142 contained therein, water bath 134 may include suitablefluids other than water 142 and still be considered to be a “waterbath.” Moreover, spray injectors 173 are coupled in flow communicationwith a fluid source (not shown), wherein such fluid that forms spraystreams 177 is compatible with the fluids within water bath 134 andstreams 177 mix within water 142 such that water 142 is considered toinclude fluids from streams 177, if any.

In the exemplary embodiment, during normal operation, the flowing syngas110 being channeled downward within dip tube 128 exerts pressure onwater 142 such that a water level L₁ in quench zone 144 is substantiallyadjacent to downstream end 154 of dip tube 128. Furthermore, dip tube128 and isolation tube 128 are each at least partially submerged inwater 142 within water bath 134. As such, water 142 at least partiallyfills first and second passages 146 and 148, respectively. Also, in theexemplary embodiment, because of pressure differences within quenchchamber 116 during normal operation, a level L₂ of water 142 withinfirst passage 146 is higher than a level L₃ of water 142 within secondpassage 148. Alternatively, levels L₂ and L₃ are substantially similar.Further, alternatively, water 142 levels L₁, L₂, and L₃ have any valuethat facilitates operation of cooler 1000 as described herein.Downstream from dip and isolation tube ends 154 and 156, respectively,sump 136 is defined within water bath 134. More specifically, sump 136may include a collection cone (not shown) coupled within shell 102 and acylindrical sump outlet 170 that extends through shell bottom 114. Water142 levels L₁, L₂, and L₃ are referenced to bottom of cooler 114 at sumpoutlet 170 and are measured via any type of level sensors thatfacilitate monitoring and controlling such levels as described herein.In the exemplary embodiment, cylindrical sump outlet 170 has a radius R₄that is shorter than cooler shell radius R₁. Sump outlet 170 may becoupled to a slag crusher (not shown), a lock hopper (not shown), a pump(not shown), and/or any other wet particulate handling and/or removaldevice that facilitates operation of system 10 as described herein.

Also, in the exemplary embodiment, blowdown line 138 extends from waterbath 134 through shell 102, and is configured to regulate the volume ofwater 142 within water bath 134. The water (not shown) that is blowndown through blowdown line 138 is normally sent to a process waterhandling system (not shown) that enables the beneficial reuse of atleast some of the blown down water. However, the blown down water may besent to any suitable component, system, and/or location that facilitatesoperation of system 10 as described herein.

During system operation, syngas 110 with particulates 112 is channeledfrom gasifier 16 to cooler 100. Syngas 110 flows through the heatexchange devices within cooler 100 and into quench chamber 116. Morespecifically, lower wall 118 of cooler 100 channels syngas 110 withparticulates 112 into primary quench zone 144, wherein syngas 110 flowspast downstream end 124 of lower wall 118 and along inner wall 174 ofdip tube 128, into water bath 134. Plugging of dip tube 128 is mitigatedby the combined effects associated with the recessed position of innerwall 174 relative to downstream end 124 of lower wall 118, therelatively lower temperature of wall 174 as compared to particulates112, which is partially cooled by water 142 external to dip tube 128,and relatively high momentums of the larger molten particles ascontrasted with relatively lower momentums of the smaller coolerparticles. Moreover, in the exemplary embodiment, quench ring 129 and/orquench spray devices wet and cool inner wall 174 of dip tube 128, aswell as facilitate cooling and scrubbing of syngas 110 and particulates112.

Particulates 112 that are solidified are referred to herein assolidified slag 176. Solidified slag 176 is formed after falling throughprimary quench zone 144 into water bath 134 and is discharged fromcooler 100 through sump 136 via sump outlet 170. Syngas 110 andremaining particulates 112 rise up through passage 146 where syngas 110is scrubbed further by one or more sprays 177, causing additionalparticulates 112 to fall and be captured in water bath 134, while syngas110 and any remaining particles 112 exit syngas cooler 100 through oneor more nozzles 140. In the exemplary embodiment, syngas 110 and/or,particulates 112 exiting water bath 134 are at a reduced temperaturerelative to syngas 110 and/or particulates 112 entering water bath 134.

Scrubbed syngas 110, which is substantially without particulate 112and/or entrained water 142, is channeled from first passage 146 throughoutlet 140 for use within system 10. In the exemplary embodiment, sprayinjector 173 sprays syngas 110 with fluid spray 177 before syngas 110 ischanneled through outlet 140. As such, the fluid from spray injector 173facilitates preventing accumulation of particulates 112 on surface 175of outlet 140 and also facilitates preventing plugging of isolation tube130, and/or outlet 140. Moreover, fluid spray 177 facilitates anyfurther separation of particulates 112 from syngas 110 and any furthercooling of syngas 110.

In the exemplary embodiment, under normal operating conditions, whereinlevel L₃ is less than level L₂, a flow of purge gas 190 may be channeledthrough cooler 100. Specifically, purge gas 190 is channeled downstreamthrough passage 148. When purge vent 147 is in an open position, purgegas 190 is channeled through purge vent 147 into isolation tube 130.Specifically, purge gas 190 is channeled upstream of water bath 134.Purge gas 190 facilitates mitigating entry of syngas 110, moisture, andparticulates 112 within sump 136 from flowing upstream into passage 148.In contrast, when purge vent 147 is in a closed position, purge gas 190remains within passage 148.

Also, in the exemplary embodiment, under backflow conditions, whereinlevel L₃ is greater than level L₂, a flow of syngas 110 withparticulates 112 are channeled through purge vent 147 into passage 148.Under such conditions, particulate matter 112 and entrained waterdroplets are removed from syngas 110 in a particle dropout zone (notshown) between vent 147 and baffle tray 155 while syngas 110 is directedtowards water bath 134. Here, under backflow conditions, baffle tray 155mitigates upward channeling of sump water 142 and entrained solids intopassage 148. The optional vent spray devices may be employed to mitigateplugging vents 147 via particulate matter 112 buildup. Moreover,similarly the optional baffle tray spray devices may also be employed.Use of vents 147 as described herein facilitates reducing a magnitude ofdifferential pressure transients within cooler 100.

In the exemplary embodiment, cooler 100 includes a dynamic pressure seal199 reproducibly formed between annular passage 146 and annular passage148 by the interaction of water 142 in water bath 134 with downstreamend 156 of isolation tube 130. Seal 199 is defined herein as “fullyengaged” when levels L₂ and L₃ are higher then the downstream end 156 ofisolation tube 130. That is, purge gas 190 and syngas 110 both areprevented from flowing between annular passages 146 (having level L₂)and 148 (having level L₃) under downstream end 156 of isolation tube 130via water 142 contained in water bath 134. Therefore, when dynamic seal199 is fully engaged, the difference in height between levels L₂ and L₃are directly related to the differential pressure across isolation tube130 between annular passages 146 and 148. Specifically, for one example,when pressure within annular passage 148 increases (for example, due toan increase in purge gas 190 supply pressure), level L₃ within passage148 will tend to decrease. If the pressure within annular passage 146and the volume of water 142 in bath 134 are held substantially constantduring the aforementioned passage 148 pressure transient, level L₂within passage 146 will tend to increase. A decrease in pressure withinpassage 146 with a substantially constant pressure within passage 148will provide a similar result. Moreover, similarly, an increase inpressure within passage 146 with substantially constant pressure withinpassage 148 will tend to decrease level L₂ and increase level L₃. Adecrease in pressure within passage 148 with a substantially constantpressure within passage 146 will provide a similar result. Therefore,when dynamic seal 199 is fully engaged, differential pressure betweenpassages 146 and 148 is directly related to a differential betweenlevels L₂ and L₃.

Seal 199 is defined herein as “partially engaged” when one of levels L₂and L₃ is adjacent to bottom end 156 of isolation tube 130 and the otherof levels L₂ and L₃ is higher than bottom end 156 of isolation tube 130.In this condition, dynamic pressure seal 199 operates substantially as aone-way seal in a manner similar to that of a selectively-operated checkvalve. That is, flow of syngas 110 underneath bottom end 156 ofisolation tube 130 is substantially reduced when L₂ is above the bottomend 156 of isolation tube 130. Specifically, a degree of flow reduction,up to and including flow prevention, under bottom end 156 of purge gas190 and syngas 110 are substantially dependent upon values for levels L₂and L₃, and pressures of purge gas 190 and syngas 110. Morespecifically, syngas 110 flow reduction is conditioned upon the combinedsealing action of a liquid head of water 142 formed between bottom end156 and level L₂, and the pressure of purge gas 190 in annular passage148. Similarly, flow of purge gas 190 underneath bottom end 156 ofisolation tube 130 is substantially reduced when L₃ is above bottom end156 of isolation tube 130. Such purge gas 190 flow is conditioned uponthe combined sealing action of a liquid head of water 142 between bottomend 156 and level L₃ and the pressure of syngas 110.

Seal 199 is defined herein as “disengaged” when both levels L₂ and L₃are downstream of, or below, bottom end 156 of isolation tube 130. Whendisengaged, syngas 110 and purge gas 190 are free to flow underneathbottom end 156 of isolation tube 130, wherein predetermined values offlow and mixing are substantially based on, and primarily controlled by,the size and geometry of the gap between liquid levels L₂ and L₃ andbottom end 156, as well as flow rates, pressures, molecular weights andtemperatures of syngas 110 and purge gas 190.

When seal 199 is engaged or partially engaged (both conditions asdefined above) the pressure drop across isolation tube 130, that is, thedifference in pressure between the pressures in annular passages 146 and148, is approximately equal to the difference in effective liquid headbetween levels L₃ and L₂. After taking into account fluid flow effects,such as the pressure drop that occurs through quench zone 144, thepressure drops across heat transfer wall 104 and the pressure differencebetween section 120 and third passage 160 are similarly related to thedifference in effective liquid head between L₃ and L₂. Consequently,seal 199 can be selectively designed and operated to provide pressureequalization means across heat transfer wall 104, lower wall 118 andisolation tube 130, thereby providing a form of overpressure protection.Furthermore, the responsiveness and magnitude of the overpressureprotection can be adjusted by modifying the volume of water 142 in waterbath 134 and the flow rate of purge gas 190. Moreover, seal 199 readilytransitions between fully engaged, partially engaged, and disengaged inresponse to such pressure drop conditions, and thereby serves as adynamic pressure seal that can provide long-term protection.

Incorporation of purge vents 147 as described above facilitates flow ofsyngas 110 and purge gas 190 above levels L₂ and L₃, and thereforeprovides means to facilitate gas flow through isolation tube 130 atlower differential pressures than would otherwise be required.Consequently, inclusion of purge vents 147 facilitates reducing a numberof occurrences wherein seal 199 is either partially engaged ordisengaged, hence reducing variations in pressure drops across heattransfer wall 104, lower wall 118 and isolation tube 130.

Although the foregoing has been described where syngas 110 passes fromannular passage 146 to annular passage 148, and purge gas 190 passesfrom annular passage 148 to annular passage 146, it should be understoodthat the gas in annular passages 146 and 148 may contain mixtures ofsyngas 110 and purge gas 190 as a normal consequence of such operation.

Operation of such seal 199 is facilitated by integrated control ofvariables that include purge gas 190 pressures and flow rates throughpassage 148 into passage 146 via vents 147 and/or under isolation tube130. Additional variables include pressures, temperatures, andcompositions of syngas 110 and particulates 112 in heat exchange section120 and primary quench zone 144, flow rates and temperatures of streams177 entering primary quench zone 144, as well as levels L₁, L₂, and L₃via blowdown line 138 and the fluid makeup line (not shown). Dynamicpressure seal 199 modulates as a function of the variables describedabove to provide overpressure protection, thus facilitating theefficient and effective syngas 110 scrubbing and cooling as describedfurther herein.

An exemplary method of assembling syngas cooler 100 for gasificationsystem 10 is provided. The method includes positioning dip tube 128within shell 102 of syngas cooler 100. Dip tube 128 is configured to atleast partially quench a portion of syngas 110 flowing through shell 102and/or channel at least a portion of syngas 110 through dip tube 128.The method also includes coupling isolation tube 130 to dip tube 128such that isolation tube 130 is substantially concentrically alignedwith, and radially outward of, dip tube 128. Isolation tube 130 iscoupled in flow communication with a source of purge gas 190 and isconfigured to at least partially form dynamic pressure seal 199. Themethod further includes coupling at least one of isolation tube 130 anddip tube 128 in fluid communication with fluid retention chamber, orwater bath 134. The method also includes at least partially filling thewater bath 134 with fluid 142, thereby further forming dynamic pressureseal 199.

Furthermore, under conditions wherein vents 147 do not have capacity tosufficiently channel purge gas 190 and/or syngas 110 into passages 146and/or 148, respectively, or under conditions wherein differentialconditions within cooler 100 are such that either L₃ or L₂ are adjacentto bottom end 156, a flow of purge gas 190 and/or syngas 110 andparticulates 112 may be channeled through a portion of water bath 134under bottom end 156. Such configuration facilitates pressureprotection, that is, differential pressure control, regardless offlow-inhibiting factors.

In alternative embodiments that do not include vents 147, under normaloperating conditions, wherein level L₃ is less than level L₂ and levelL₃ is substantially adjacent to downstream end 156, a flow of purge gas190 may be channeled downstream through passage 148 into isolation tube130. Specifically, purge gas 190 is channeled through a portion of waterbath 134 into passage 146 under end 156. Under backflow conditions,wherein level L₃ is greater than level L₂ and level L₂ is substantiallyadjacent to downstream end 156, a flow of syngas 110 and particulates112 may be channeled through a portion of water bath 134 into passage148 under end 156. Under such conditions, particulate matter 112 isremoved from syngas 110 in a particle dropout zone (not shown) betweenlevel L₃ and baffle tray 155. Lack of vents 147 may facilitate anincrease in the magnitude of differential pressure transients withincooler 100. However, such configuration facilitates pressure protection,that is, differential pressure control regardless of no vents 147.

FIG. 3 is a schematic cross-sectional view of an alternative syngascooler 200 that may be used with system 10 (shown in FIG. 1). Syngascooler 200 includes at least one dip tube 228, at least one isolationtube 230, and at least one outlet 240. Cooler 200 is similar to cooler100, and similar components are identified in FIG. 3 using the samereference numerals used in FIG. 2. More specifically, dip tube 228 issimilar to dip tube 128 and identical components are identified with thesame reference numerals used in FIG. 2, isolation tube 230 is similar toisolation tube 130 and identical components are identified with the samereference numerals used in FIG. 2, and outlet 240 is identical to outlet140 and like components are identified with the same reference numeralsused in FIG. 2.

In contrast to dip tube 128, dip tube 228 is frusto-conical.Specifically, as shown in FIG. 3, an upstream end 250 of dip tube 228 iscoupled in close proximity to upstream end 151 of splash plate 132, anda downstream end 254 of dip tube 228 is upstream from downstream end 256of isolation tube 230. Upstream end 250 defines a radius R₅ anddownstream end 256 defines a radius R₆ that is larger than radius R₅ andsmaller than radius R₃. As such, dip tube 228 diverges from upstream end250 towards downstream end 254. The size of radius R₆ enables downstreamend 254 to provide the same amount of quenching as downstream end 154,while shortening a distance L₄ dip tube 228 is submerged within waterbath 134, wherein, L₄ is the difference between L₁ and L₂. Any means forquenching, scrubbing and cooling syngas 110, cooling and flushingradially interior portions of dip tube 228, and cooling and flushingother components in cooler 200 are provided.

Cooler 200 operates in a manner that is substantially similar to theoperation of cooler 100.

Referring to FIGS. 2 and 3, alternate embodiments of isolation tubes 130and 230 include a plurality of openings 300 and 400, respectivelydefined within downstream ends 156 and 256, respectively. Specifically,such openings 300 and 400 are defined at predetermined elevations abouta circumferential portion of isolation tubes 130 and 230 defined by thedifference between lengths L₁ and L₂ and radius R₃. Plurality ofopenings 300 and 400 facilitate a predetermined distribution of purgegas 190 through tubes 130 and 230 from passage 148 into passage 146under normal operating conditions, wherein level L₃ is less than levelL₂, and L₃ is at substantially the same level as one or more of theopenings 300 and 400 through tubes 130 and 230, respectively.

Moreover, such openings 300 and 400 facilitate a predetermineddistribution of syngas 110 through tubes 130 and 230 during backflowconditions, wherein level L₃ is greater than level L₂, and L₂ is atsubstantially the same level as one or more of the openings 300 and 400through tubes 130 and 230, respectively. Under such conditions,particulate matter 112 is removed from syngas 110 in a particle dropoutzone (not shown) between level L₃ and baffle tray 155. Use of openings300 and 400 as described herein facilitates reducing a magnitude ofdifferential pressure transients within coolers 100 and 200. Moreover,bypassing downstream portions 156 and 256 of isolation tubes 130 and260, respectively, facilitates a more gradual equalization of pressureacross tubes 130 and 230. Openings 300 and 400 may be used in additionto, or in lieu of, vents 147 and have any configuration that facilitatesoperation of syngas coolers 100 and 200 as described herein.

Referring to FIGS. 2 and 3, alternate embodiments of coolers 100 and 200include operation with level L₂ below downstream ends 154 and 254 of diptubes 128 and 228, respectively. However, such alternative embodimentsalso include operation with level L₃ above downstream ends 156 and 256of isolation tubes 130 and 230, respectively. Such operation is referredto as “partial quenching”, wherein flow of syngas 110 from dip tubes 128and 228 receives little to no quenching via water 142 in bath 134.However, partial quenching of syngas 110 and partial cooling of diptubes 128 and 228 may be facilitated with water or gas quenching fromdevices similar to quench ring 129 (shown in FIG. 2). Also,alternatively, similar quenching devices may be positioned withinpassage 146 prior to outlets 140 and 240 to facilitate quenching ofsyngas 110 prior to entry into outlets 140 and 240 as well as partialcooling of dip tubes 128 and 228, wherein such quenching and coolingoperation may be performed in conjunction with spray injectors 173.Further alternatively, any configuration of quenching devices thatfacilitates operation of such alternative embodiments as describedherein are used. Also, alternatively, any configuration of dip tube 128and 228 cooling mechanisms that facilitates operation of suchalternative embodiments as described herein are used, including, but notlimited to, indirect cooling methods such as evaporative cooling ofshell 102. Moreover, such alternative embodiments retain dynamicpressure seal 199, wherein such operation includes maintaining level L₃above downstream ends 156 and 256 of isolation tubes 130 and 230,respectively.

Again, referring to FIGS. 2 and 3, alternate embodiments of coolers 100and 200 include use of a draft tube (not shown) as is known in the art.Such alternative embodiments may also include draft tube cooling andsyngas quenching as described herein.

The above-described radiant syngas cooler (RSC) reduces a temperature ofa syngas and/or particulate flow. Specifically, the temperature of thesyngas and/or particulates is reduced as the syngas is routed through adip tube, an isolation tube, and an outlet. The outlet includes at leastone spray injector therein that sprays the syngas with water before thesyngas is channeled through the outlet. Spraying the syngas prior tochanneling the syngas through the outlet facilitates preventing pluggingand/or fouling of the radially outer surfaces of the dip tube, radiallyinner surfaces of the isolation tube, and the inner walls of the outlet.With less plugging and/or fouling of surfaces within the syngas cooler,the syngas cooler requires less maintenance, and the efficiency of thecooler is improved such that a convective syngas cooler (CSC) is notrequired. Moreover, suspended particulates and/or particles within thesyngas flow and/or fly ash are separated and/or precipitated and/orquenched through contact with water. Particularly, the particulatesand/or particles are cooled by contact with a water bath. Further, theabove-described syngas cooler includes at least one splash plate, atleast one spray injector, and at least one baffle tray that facilitatepreventing and/or lessening non-evaporated entrained water droplets thataccumulate on components of the syngas cooler during operation of thesyngas cooler. Also, vents as described herein facilitate pressurecontrol and differential pressure control within the cooler to maintaina margin to operational limits and to facilitate effective heat transferand syngas scrubbing. Furthermore, formation and operation of a dynamicpressure seal within the RSC facilitates pressure and differentialpressure protection of syngas cooler components and overall operation ofthe RSC to efficiently effect the aforementioned features andcharacteristics.

Exemplary embodiments of a syngas cooler are described above in detail.The syngas cooler is not limited to the specific embodiments describedherein, but rather, components of each syngas cooler may be utilizedindependently and separately from other components described herein.Each syngas cooler may also be used in combination with other systems,and is not limited to practice with only the system described herein.Rather, the present invention can be implemented and utilized inconnection with many other quenching applications. For example, eachsyngas cooler may be used not only with an IGCC power generation plant.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A method of assembling a synthesis gas (syngas) cooler for agasification system, said method comprising: positioning a dip tubewithin a shell of the syngas cooler, wherein the dip tube includes anupstream end and a downstream end, the dip tube is configured to atleast one of: at least partially quench at least a portion of the syngasflowing through the shell; and at least partially channel at least aportion of the syngas through the dip tube; coupling an isolation tubeto the dip tube such that the isolation tube is substantiallyconcentrically aligned with, and radially outward of, the dip tube,wherein the isolation tube includes an upstream end and a downstreamend, the dip tube downstream end is positioned upstream from theisolation tube downstream end, and wherein the isolation tube is coupledin flow communication with a purge gas source and is configured to atleast partially form a dynamic pressure seal; coupling at least one ofthe isolation tube and the dip tube in fluid communication with a fluidretention chamber; and at least partially filling the fluid retentionchamber with fluid, thereby further forming the dynamic pressure seal.2. A method in accordance with claim 1 further comprising: coupling atleast one syngas outlet to the shell, wherein the outlet is configuredto channel a portion of syngas from the isolation tube; and coupling atleast one spray nozzle within the at least one syngas outlet.
 3. Amethod in accordance with claim 1 further comprising defining at leastone purge vent within the isolation tube.
 4. A method in accordance withclaim 1 further comprising defining a plurality of circumferentialopenings within at least a portion of the isolation tube.
 5. A synthesisgas (syngas) cooler for use within a gasification system, said syngascooler comprising: a shell; a dip tube positioned within said shell,said dip tube comprising an upstream end and a downstream end, said diptube is configured to at least one of: at least partially quench atleast a portion of a syngas flowing through said shell; and at leastpartially channel at least a portion of the syngas through said diptube; an isolation tube comprising an upstream end and a downstream end,said isolation tube coupled to said dip tube such that said isolationtube is substantially concentrically aligned with, and radially outwardof, said dip tube, wherein said dip tube downstream end is positionedupstream from said isolation tube downstream end, and wherein saidisolation tube is coupled in flow communication with a purge gas sourceand is configured to at least partially form a dynamic pressure seal;and a fluid retention chamber coupled in flow communication with atleast one of said isolation tube and said dip tube, wherein said fluidretention chamber is at least partially filled with fluid and isconfigured to further form said dynamic pressure seal.
 6. A syngascooler in accordance with claim 5 further comprising: at least onesyngas outlet coupled to said shell, said syngas outlet configured tochannel a portion of the syngas from said isolation tube; and at leastone spray nozzle coupled to said at least one syngas outlet.
 7. A syngascooler in accordance with claim 6 wherein said at least one syngasoutlet is positioned between said shell and at least one splash plate,wherein said at least one splash plate is coupled to said isolationtube.
 8. A syngas cooler in accordance with claim 5 wherein at least oneof said dip tube downstream end and said isolation tube downstream endis serrated.
 9. A syngas cooler in accordance with claim 5 wherein saidisolation tube downstream portion defines a plurality of circumferentialopenings.
 10. A syngas cooler in accordance with claim 5 wherein saiddownstream end of said dip tube is one of: at least partially immersedwithin the fluid within said fluid retention chamber; and positionedupstream of the fluid within said fluid retention chamber.
 11. A syngascooler in accordance with claim 5 wherein said dip tube is one of acylindrical and frusto-conical configuration.
 12. A syngas cooler inaccordance with claim 5 further comprising a syngas chamber definedupstream from said dip tube such that said syngas chamber is configuredto channel syngas into said dip tube.
 13. A syngas cooler in accordancewith claim 5 further comprising at least one baffle tray coupled withinsaid shell.
 14. A syngas cooler in accordance with claim 5 furthercomprising at least one purge vent defined within said isolation tube,wherein said at least one purge vent is one of fixed opening andselectively operable configurations.
 15. A syngas cooler in accordancewith claim 5 further comprising at least one seal positioned betweensaid syngas outlet and said isolation tube.
 16. A syngas cooler inaccordance with claim 5 further comprising at least one quenchingmechanism.
 17. A gasification system comprising: at least one gasifierconfigured to produce a synthesis gas (syngas); and at least one syngascooler coupled in flow communication with said gasifier, said at leastone syngas cooler comprising: a shell; a dip tube positioned within saidshell, said dip tube comprising an upstream end and a downstream end,said dip tube is configured to at least one of: at least partiallyquench at least a portion of the syngas flowing through said shell; andat least partially channel at least a portion of the syngas through saiddip tube; an isolation tube comprising an upstream end and a downstreamend, said isolation tube coupled to said dip tube such that saidisolation tube is substantially concentrically aligned with, andradially outward of, said dip tube, wherein said dip tube downstream endis positioned upstream from said isolation tube downstream end, andwherein said isolation tube is coupled in flow communication with apurge gas source and is configured to at least partially form a dynamicpressure seal; and a fluid retention chamber coupled in flowcommunication with at least one of said isolation tube and said diptube, wherein said fluid retention chamber is at least partially filledwith fluid and is configured to further form said dynamic pressure seal.18. A gasification system in accordance with claim 17 furthercomprising: at least one syngas outlet coupled to said shell, saidsyngas outlet is configured to channel a portion of the syngas from saidisolation tube; and at least one spray nozzle coupled to said at leastone syngas outlet.